Nitrogen Fixing Activity of Endophytic Bacteria Associated with Kalanchoe pinnata (Lam.) and its effect on Zea mays

Abstract

ABSTRACT: Nitrogen is essentially required for the plant growth as well as productivity. Plants take nitrogen in the form of ammonia or nitrate either from soil or fertilizer. There are nitrogen fixing bacteria plays a vital role to supply atmospheric nitrogen to plants where plants do not obtain from soil. Apart from soil bacteria, endophytic bacteria which living inside the plant tissues can improve crop productivity and soil health sustainably through biological nitrogen fixation and act as a potential replacement for chemical fertilizers in agriculture. This study was conducted to determine the nitrogen fixing activity of isolated endophytic bacteria from Kalanchoe pinnata (Lam.). The isolated endophytes were subjected to molecular confirmation and evaluated for ammonia production, Acetylene Reduction Assay (ARA), nif gene amplification and analysis of growth parameters in Zea mays using pot culture assay. The data were analyzed using SPSS ver.16. In this study, Bacillus thuringiensis, Bacillus paranthracis, Staphylococcus xylosus and Bacillus cereus were isolated from the leaves of Kalachoe pinnata (Lam). They were confirmed using 16SrRNA sequencing. All the endophytic bacteria were positive for ammonia production and ARA. The percentage of nitrogen produced was 32.8 % (B. thuringiensis), 65.7% (B. paranthracis), 80.7% (S. xylosus) and 45.2% (B. cereus).The presence of nif gene was confirmed through the PCR amplification of a 550-580bp fragment of the gene. Pot culture assay of Zea mays were observed with significant improvement in S. xylosus followed by B. paranthracis inoculated pots. The presence of the nitrogenase enzyme and the nif gene in these endophytic bacteria allows them to fix atmospheric nitrogen to meet plant nitrogen demands, resulting in a symbiotic relationship with agricultural crops.